JPS61146546A - Liquid jet recording apparatus - Google Patents

Abstract

PURPOSE:To rapidly and simply optimize a printing state, by providing an exclusive controller for controlling the emission of a head unit and performing preparatory emission processing at the start time of a printer by said controller. CONSTITUTION:At the beginning of printing, a liquid jet recording head unit HU is subjected to preheating treatment and preparatory emission processing to improve an ink emitting state. After preheating was stopped, said recording head unit HU is allowed to stand by for a predetermined time to average the temp. distribution in the locally heated recording head HU and, subsequently, preparatory emission processing is performed. An emission condition is set to a head unit controller 10 and printing output to all dots is set to '1'. Printing output is applied to the recording unit HU to perform emission and this operation is repeated prescribed times. After the completion of this operation, the recording head HU is transferred to a stand-by state. When a printing signal is supplied from a host computer in said stand-by state, printing data is latched by PPI1 and transmitted to RAM3 being a line buffer. Then, the signal from a temp. detection element TS is detected by a temp. comparing circuit 15 to judge whether a low temp. side is a definite temp. or more.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid jet recording device that performs recording by ejecting liquid to form ejected droplets and attaching the droplets to a recording material such as paper, and particularly relates to The present invention relates to a liquid jet recording device that applies ejection energy to liquid to form ejected droplets.

[Prior art] Liquid jet recording method (inkjet recording method).

This is a recording method in which ejected droplets of recording liquid are formed using various methods, and the droplets are attached to a recording material such as paper to perform recording.

Among recording devices (printers) that apply such recording methods, a type of liquid that uses heat as energy to form ejected droplets is a device that has a structure suitable for high-density multi-orifice recording heads. Injection recording device 11
(hereinafter referred to as an inkjet printer).

Inkjet printers that use heat as the energy for ejecting droplets usually heat the recording liquid to give it a displacement that causes a sudden increase in the body 81 so that it can flow from the orifice (droplet ejection hole) of the nozzle. A droplet forming means for ejecting and forming recording liquid droplets, and an electrothermal energy conversion element (hereinafter referred to as an ejection heater) that can generate heat and heat the recording liquid by applying an electric signal. The recording head is equipped with a recording head.

On the other hand, the recording liquid used when recording with an inkjet printer has different recording properties.

Water-based recording liquids are mainly used for safety reasons.

This aqueous recording liquid is generally formed of a recording agent such as a pigment or dye, and a solvent component mainly consisting of water or water and a water-soluble organic solvent for dissolving or dispersing the recording agent.

In the above-mentioned printers that use heat as droplet ejection energy and other printers that apply droplet formation methods, the orifice provided at the tip of the nozzle from which recording liquid is ejected is constantly AM is often open to the outside air.

For this reason, if recording is not performed for a long period of time, water or volatile organic substances such as water or volatile organic matter may be removed from the recording liquid that has accumulated in the orifice and its vicinity, since an aqueous recording liquid is used as described above. Solvent components such as solvent evaporate from the orifice into the outside air, and recording agent components and solvent components that are difficult to volatilize remain in the recording liquid, increasing the viscosity of the recording liquid retained in this area, and as a result, the recording liquid Immediately after restarting recording, a droplet ejection failure is likely to occur in which droplets are not ejected even though an ejection signal is applied, and recording There is a problem in that defects occur in the initial printed portion of the image.

Additionally, some printers cap the ejection surface with an orifice when the device is not in use, such as when the power is off, but even with this type of capping, the orifice is not completely isolated from the outside air. Since there is no,
The above problem also occurs in such printers.

On the other hand, in order to obtain a good droplet ejection condition even when the viscosity of the recording liquid increases at low temperatures, the temperature of the recording liquid can always be maintained within a predetermined range.

Japanese Patent Laid-Open No. 58-187 discloses a recording method that heats the recording liquid by constantly applying an electrical signal to the ejection heater at a level at which no recording droplets are ejected even when no droplet ejection signal is applied.
Known by No. 384.

However, even in printers using this type of system, an electrical signal is applied to the ejection heater so that the recording liquid is always kept at a high temperature even during a relatively long recording pause or stop period. Evaporation of solvent components in the liquid occurs more easily.

In some cases, a problem arises in that droplet ejection failure is more likely to occur when recording is resumed as described above. In addition to this,
In this method, since the area around the ejection heater is constantly heated, the durability of the parts around the ejection heater may be impaired, or the recording liquid itself may remain around the ejection heater during the recording pause period. Changes in physical properties due to the heat may occur, causing problems such as discoloration of the recording liquid or the formation of precipitates in the recording liquid, clogging the orifice and causing droplet ejection failure.

In addition, immediately after the printer is turned on, the temperature of the ink liquid involved in recording is controlled by environmental conditions such as atmospheric temperature, so starting recording by discharging ink immediately after turning on the power does not ensure stable printing conditions. It's not a desirable thing to get.

Therefore, an alternative is to configure an inkjet printer that performs preliminary ejection after the power is turned on and before printing starts, ejecting the old ink that was at the tip of the nozzle before the power was turned on to optimize ejection. .

However, in the past, print output was performed from a microprocessing unit (MPU) that controlled each part of the printer via a port IC. Since it is extremely difficult to precisely control this, there is a problem in that optimal preliminary ejection cannot be performed.

[Objective] The present invention eliminates such conventional problems by providing a dedicated controller for controlling ejection of the head unit, and using the controller to perform preliminary ejection processing when starting up the printer. An object of the present invention is to provide an inkjet printer that can quickly and easily optimize printing conditions.

[Structure of the Invention] In order to achieve the above object, the present invention, as shown in FIG. A liquid jet recording unit 1 which has a generating means 102 and performs recording on a recording material P by ejecting the Wj-formed flying droplets.
00 and an electric signal can be set, and the recording unit control means 110 supplies an electric signal that causes the ejection energy generation means 102 to form flying droplets in response to the input of the recording signal SA.
and an ejection control means 150 for ejecting flying droplets from the liquid jet recording unit 10G by setting an electric signal for forming flying droplets in the recording unit control means 110 when the power is turned on. Features.

[Example] The present invention will be described in detail below with reference to one drawing.

FIG. 2 shows an example of the configuration of the recording section of an inkjet printer to which the present invention can be applied. This example shows the present invention applied to an inkjet printer in which a head unit is mounted on a carriage that moves in a predetermined direction with respect to the recording surface. It was applied. In addition, FIGS. 3(A) and (B) are, respectively,
3 is an enlarged view of the head unit in FIG. 2, and a further enlarged view of its nozzle portion. FIG.

In these figures, HU is a liquid ejecting unit mounted on a carriage C, and the number of units can be provided depending on the ink color used. FC is the liquid injection unit,)
It is a flexible cable that collects signal lines etc. that control ink ejection by MU.

The carriage C is fixed to a belt or the like, for example.

It moves in the S direction in the figure by a driving means such as a motor.

R is a guide rail that guides the movement of the carriage C in the S direction.

In addition, P is a recording material such as paper that is conveyed in the f direction in the figure,
PL is a platen that forms the recording surface of the recording paper P. That is, the carriage 7C is driven by the guide rail R by the driving means.
Move along in the S direction in the figure.

Recording can be performed on the recording surface.

ST is a sub-tank provided in the carriage C, TBI and τB2 are ink supply pipes that communicate the main tank (not shown) and the sub-tank ST, and communicate the sub-tank ST with the liquid chamber IR in the HIT, respectively. This is an ink supply pipe unit.

Also, CAP is a cap member, and is located in the S direction.

The carriage C is arranged to face the liquid jet recording unit (7) HU at the home position NH, and when the carriage C is at the home position, the cap member CAP is directed toward the liquid jet recording unit (7) HU by a driving means such as a motor. and move
It can be made to come into contact with the discharge surface. SP
is a collection member that comes into contact with the ejection surface of the HU to collect ink, and is made of, for example, a water-absorbing porous material.

In Figure 3 (A), BP is the supply pipe (22) 82
, liquid chamber IR, nozzle part NZ, flexible cable FC, etc. are arranged, the base plate to support these, EsH is the elastic member to support the nozzle part periphery, FP is the front plate, 0-piece S is the temperature detection Temperature sensor such as a thermistor for use in the head unit;
P is a heat conductive plate.

Further, in FIG. 3(B), OR is an orifice serving as an ink discharge hole, and in this example, a predetermined number of orifices OR are arranged in one direction in the nozzle portion NZ. IC) I is orifice OR and liquid chamber! The liquid flow path communicating with R is an ejection heater serving as an ejection energy generating element that provides thermal energy for ejection to the ink in the liquid flow path ICH.

To perform recording using this equipment, first, ink is supplied from the main tank to the five sub-tanks via the supply pipe TBI, and then to the liquid chamber I via the supply pipe unit TBI.
Next, a flexible cable F is connected from a signal generating means for droplet ejection, which will be described later, to fill recording liquid into R and liquid flow path ICH.
An electric signal is applied via C to energize the discharge heater E. As a result, the ejection heater E generates heat, and thermal energy is applied to the recording liquid in the liquid flow path ICH near the ejection heater ET.

At that point, bubbles are generated in the recording liquid accompanied by an instantaneous increase in the volume of the recording liquid, and the recording liquid located downstream of the discharge heater E is discharged from the Oriice OR. droplets are formed. Recording is performed by making droplets of the recording liquid adhere to a recording material P such as paper that has been sent in front of the nozzle section.

FIG. 4 shows an example of the configuration of a control device for an inkjet printer according to the present invention. This control device receives print data from, for example, a host combiner, stores print data for one line, and prints data from a head unit. It is assumed that printing is performed by controlling the print head using the 'lU controller.

First, %l is a programmable peripheral interface (hereinafter referred to as PPI), which functions to receive print data sent from the host computer of the printer according to this example in parallel, and send the print data to MPU2.
Also, 2 is a microprocessing unit (hereinafter referred to as NPU) that controls the console 6 and performs input processing for the home position sensor 7, and 3 is a PPII that controls various parts in the printer and performs the processing procedures described later. A RAM serves as a line buffer memory for storing one line of received print data, 4 is a ROM for the font of print output characters, and 5 is for control in which processing method II (Figs. 5 to 7) executed by the MPU 2 is stored. It is a ROM. These units 1 to 5 are connected via an address bus AB and a data bus DB.

6 is a console having a keyboard switch, an indicator lamp, etc., and 7 is a home position sensor provided near the home position of the carriage C. 8 is a cap mode switch for detecting the state of the cap member CAP, that is, opening/closing of the cap with respect to the head HIJ, and 9 is a paper sensor for detecting the absence of printing paper.

1O is a controller for the head unit, latches print data and print output time, and starts print output in response to a command from the MPU 2. That is, in this example, the controller 10 is used as a dedicated IC circuit to speed up the processing. As this controller 10, for example, the one disclosed by the applicant in Japanese Patent Application No. 162802/1988 can be used. In addition, 1
Print data that has been bordered multiple times is output as is if there is no need to change it.

11 is a driver for driving the head unit Hu in response to the controller 10; 13 is a protection circuit for the head unit HU; Reference numeral 14 denotes a driver for driving the ink heating/warming heater HTR provided in the head unit (HU). 15 is a temperature comparison element of the ink temperature comparison element S provided in the head unit HU. 1g is a switch for instructing switching of printing fonts. 17 is a temperature comparison circuit 15. This is a signal input switching device for the switch 16, and is controlled by the MPU2.

A driver 18 drives a motor M3 for moving the cap member CAP relative to the head unit HU. 22 and 24 are motors N for feeding one paper, respectively.
1 and a motor M2 for moving the carriage. Also, 20 and 2! are a solenoid for a valve used to vent air in the head unit (HU) and its driver, respectively.

Now, regarding this example! There is no J2 diagram! 4Ug! An overview of the processing in the shown inkjet printer will be described below. In this example, when the power of the printer is turned on and when printing is started, the head unit (HU) is subjected to preliminary heating processing and preliminary ejection processing to improve the ink ejection state. Furthermore, in connection with these processes, capping of the unit HU is appropriately controlled. For preliminary heat treatment.

External heat treatment and/or internal heat treatment shall be performed.

Here, external heating refers to heating the ink in the head unit HU from the outside by driving the heater HTR, and internal heating refers to ejecting print output pulses within a range in which ink is not ejected from the HU. During internal heating, which refers to heating from inside the head by supplying energy to the energy generating element, a print output start signal is sent to the head unit controller 10 at each set frequency.

When performing preheating, especially internal heating, the head unit HU outputs a printout with an appropriate pulse width, frequency, and voltage.
However, by using the head controller 10, sufficient processing is possible even at a processing speed of 1 normal HPυ.

That is, according to this example, the parameters of each print output can be freely changed and set as necessary, so that optimal head heating and software simplification and speeding up can be achieved.

Also, when preliminary ejection is performed, it is preferable to similarly apply an appropriate print output to the head unit MU using the pulse width 1 frequency and voltage as parameters. In this example, these parameters and the number of ejections are changed depending on the environmental conditions.

According to this example, such a case can be easily handled by software, and optimal preliminary ejection becomes possible. Further, in this example, the print output during preliminary ejection was set to "1" for all dots using the head controller IO. Therefore,
Regarding the print data in this case, it is not necessary to change the print data each time, so it is possible to simplify the software and speed up the processing.

The print state optimization process in one example will be described below.

wIJ5 Figures (A) and CB) show an example of a print state optimization processing procedure according to the present invention.

Immediately after the printer is powered on, as an initial process.

The hardware initializes the PPII and head unit controller 10, and the software initializes the line buffer memory RAM 3, checks the operation of the control ROM 5, and initializes each parameter used in processing. Step 51).

After this initial processing is completed, the head cap motor M3 is operated while monitoring the gap mode switch 8 by HPυ2, and the head cap opening processing is performed (step S2
), and operates the carriage motor M2 while monitoring the home position sensor 7 to move the carriage C and position it at the home position H (step S3).
, and while monitoring the cap mode switch 8,
The cap motor M3 is operated to perform head cap closing processing for the head unit HU (step S0. Furthermore, the motor N1 is driven to feed the paper for one line, for example. After these processes, the head unit) is initialized for the HU. Perform processing.

In the initial processing, first, preliminary heating processing (step SH) of the head unit HU is started.

FIG. 6 shows an example of a preheating process procedure for external heating and internal heating. As mentioned above, internal heating is performed by controlling the controller 10 to output pulse widths, voltages, and high frequencies within a range that does not eject ink. In addition to HU,
External heating refers to each time heat is generated internally, and external heating refers to heating the head unit HU by turning on the driver 14 from the NPU 2 using the heater HTR provided in the head unit HU as a heating element. Step 5)
In II, external heating is started, and in step SH2 the head unit controller IO is set to external heating mode (0, then step S)! Set the print output to "l" for all dots in step 3, and then proceed to step 5)14.
Start internal heating at . During this internal heating, the pulse width of the print output and the tt pressure are controlled as described below.

Make sure to set the frequency appropriately.

Once you start preheating the head like this.

The temperature of the head unit HU is measured, and if the temperature of the HU is equal to or higher than a certain temperature on the high temperature side (step 5H5), the preheating is ended. If preheating is started and the high temperature does not exceed a certain temperature even after a certain period of time has passed (step 5HO), an internal heating stop command is sent to the controller 10 in step SH7 to prevent thermal damage to the head. Stop heating 1
Next, in step SH8, the driver I4 is turned off to stop external heating. That is, at this time, the preheating is stopped and the process returns to step S6 in FIG. 5(A). It should be noted that the constant temperature on the high temperature side refers to the upper limit operating temperature of the head unit 12 (for example, 42° C.), and it goes without saying that the order of starting and stopping the external heating 1 and 8 and the internal heating may be in any order.

Referring again to FIG. 5, after stopping the preheating, for a predetermined period of time,
After waiting, the temperature distribution inside the HU is averaged (step S6), and after this waiting, preliminary ejection processing (step SJ) is performed. When heat treatment is performed, the standby time may be set to a relatively long time; in this case, it may be set to, for example, 500 as.

FIG. 7 shows an example of the preliminary ejection processing procedure. Here, first, in step SJI, the head unit controller 1
The ejection conditions are set to 0, and then, in step SJ2, the print output for all dots is set to 1. Then, in step SJ3, the print output is output from the head unit, )Hll.
In addition to this, ejection is performed, and this is turned over a predetermined number of times by the process of step 2 SJ4, and after the completion of the process, the process returns to step 510 in FIG. 5 and shifts to a print standby state. That is, the initial processing for the head unif (HU) is completed, and one step moves to a print standby state from the host computer. Note that the specified discharge times a8 and the parameters of the discharge conditions can be appropriately set depending on the environmental conditions as described later.

When a print signal is supplied from the host computer in the print signal standby state (step 510), the print data is P
RAM3 latched to PII and used as a line buffer
will be forwarded to. Therefore, the temperature comparison circuit 15 detects a signal from the temperature detection element S provided in the head unit (head unit) HU, and determines whether or not the temperature is higher than a certain temperature on the low temperature side (for example, 20°C or higher) (step 5ll). If the determination is affirmative, the head cap motor M3 is driven to perform the cap opening process (step 512), and then the controller ]O is set to the normal printing mode and preliminary ejection is performed (step SJ, see FIG. 7). On the other hand, if it is determined that the low temperature is lower than the certain temperature, the cap is opened (step 913).
After performing the preheating treatment (step SH; see FIG. 6), wait for a predetermined time [step 515]! , after
Further, the discharge conditions and the number of discharges are set in the controller 10 to perform preliminary discharge (see FIG. 7 for step S).

Note that the standby time in this case can be made shorter than the above-mentioned standby time when rapid heating is not performed such as during startup. Note that the temperature on the low temperature side should be constant (Step 7 51G)
, moves to printing state. That is, carriage motor M
The heat treatment is not performed during the printing operation when the printer 2 is being driven.

Further, heat treatment can also be performed without increasing power consumption in connection with the printing process in step S20. That is, when the carriage C is in operation and changes direction of movement at both ends of the carriage movement range, the carriage C stops there.

Heat treatment may also be performed.

When printing is started and the printing for 1, for example, - character is performed and the carriage motor M2 is stopped (step 520),
It is determined whether the temperature of the head unit HU is equal to or higher than a certain temperature on the low temperature side (step 521).

If the judgment is positive here, the process moves to the next step, and if the judgment is negative, the driver 14 is turned on and external heating is started (
The process proceeds to step 522). That is, it is determined whether the temperature of the head unit HU is equal to or higher than a certain temperature on the high temperature side (step 523).

Here, if the judgment is positive, immediately, if the judgment is negative, after waiting for a predetermined time (for example, 200 m5) (step 5).
24), stop external heating (step 525).

Next, as shown in FIG. 5(B), the paper feed motor Ml is driven to feed the paper (step 530), and the process proceeds to the next stage through steps 531 and S32, which are similar to steps S21 and S22, respectively. Transition. i.e. lMPU
2, the internal timer is turned on and it is determined whether the print data is latched to PPrl within a predetermined time (for example, within 5 seconds) (steps 540, 541), and if the determination is affirmative here, as shown in FIG. 5(A). The process moves to step S+6. On the other hand, if the determination is negative, the dry air 4 is turned off and external heating is stopped (step 542).

After driving the carriage motor M2 to position the carriage C at the home position H (step 543), and then driving the cap motor M3 to perform cap closing processing (step 544), step 510 in FIG. 5(A) is performed. to return to.

In this way, in this example, after the preliminary heating process, the preliminary ejection process of ejecting droplets that are not used for recording is performed, so the recording pause or stop period becomes very long, and the evaporation of the solvent component Even if the viscosity of the recording liquid increases significantly due to the above, it is possible to optimize ejection during printing. That is, first, the high viscosity portion of the recording liquid is heated by the preheating process, and its temperature is increased, and the viscosity of the recording liquid is lowered to the extent that droplets can be ejected.

By performing the preliminary ejection process in this state, the recording liquid in this area is ejected out of the liquid flow path ICH.
Recording liquid whose viscosity is within a suitable range for ejection is supplied near the ejection heater ET, and a good recording liquid ejection condition can be obtained from then on. In order to confirm the stability of this discharge state, the applicant conducted the following experiment.

[Experiment using Example] 24 orifices (orifice diameter 50 x 40 JLm)
Using an inkjet printer according to this example, which has a recording head section as shown in FIG. Fill the device.

Recording pause MM for 12 hours in an environment of 25°C and 30% RH
When recording is restarted later, the voltage is 23.5V and the pulse intensity is 5.
A signal with a voltage of 23.5 V, a pulse width of tops, and a frequency of 2 KHz is applied to the ejection heater ET for 100 pulses to generate a droplet that is not used for recording. By ejecting the recording liquid and measuring the number of non-ejected droplets with respect to the recording signal until the droplets of the recording liquid used for recording are ejected from all 24 orifices, we can evaluate the recording device regarding ejection failure after recording is stopped. went. The results are shown in Table 1.

The composition of the recording liquid used for recording is as follows.

C, 1, Direct Black 13 2 parts by weight diethylene glycol 30 parts by weight water
70 parts by weight [Experiment using comparative example] Same structure as in the example, but for recording.

A two-layer device in which only the electric signal for ejecting the recording droplets used for recording is applied to the ejection heater was used, and the above-mentioned recording liquid was filled into the device, and the temperature was set at 25°C and 30% RH for 12 hours.
When resuming recording after a time recording pause period, the voltage 23
．． Recording was performed by applying only an electric signal for droplet ejection of 5 V, pulse intensity 10 kHz, frequency 2 kHz to the heater,
In the same manner as in the experiment using the example, this device was evaluated regarding ejection failure after recording was stopped. The results are shown in Table 1.

ゝ-8 Table 1 In this way, even when recording is resumed after a particularly long recording stop or stop period, a good and stable droplet ejection condition can always be obtained.

Next, the settings of parameters such as the pulse width, frequency, voltage, etc. of the print output in the preliminary heating process and the preliminary ejection process will be described.

How long is the recording pause or stop time for the liquid flow path ICH?
Whether the viscosity of the recording liquid, especially near the orifice OR, deviates from the preferred range depends on the characteristics of the device used, the physical properties of the recording liquid, and the temperature and humidity of the location where the device is installed and used. Since each device is different depending on the environmental conditions, etc., the parameters of print output during preheating, especially internal heating treatment, are appropriately selected depending on the individual device and its usage condition.

In addition, the signal supplied to the ejection heater ET in the preliminary ejection process is set under such conditions that the recording liquid whose viscosity is not in the range suitable for ejecting droplets during recording can be ejected and removed to the outside of the liquid flow path ICH. so that it is applied.

Furthermore, the number of ejections in the preliminary ejection process is made variable depending on the environmental conditions at that time, so that efficient processing can be performed.

FIG. 8 shows the electrical signal applied to the discharge heater ET, where ma0 is the voltage and w+ is the pulse width. If a bubble is generated due to heating when a signal is supplied to the 8 ejecting pins during the preheating process, subsequent ejection of droplets may become unstable, or in some cases, non-ejection may occur. There is also. Therefore, the electric signal applied to the 8 pieces of beef for delivery during preheating must be within a range that does not generate bubbles on the 8 pieces of the delivery heater.

On the other hand, since these preheating treatments are set when the printer is turned on or when printing starts, the frequency of use of preheating is extremely high.Therefore, these preheating treatments degrade the durability of the 8 sheets for ejection. In the preliminary heating process using the discharge heater ET, the inventors have determined that the power (W) applied to the discharge heater ET is
) was kept constant, and the durability of the discharge heater ET was examined when the pulse intensity Wi and the applied voltage Ma0 were varied.
The smaller the pulse intensity Wi and applied voltage Ma0, the smaller the heater ET.
It was confirmed that the durability of

Next, the time required to heat the head unit HU to the desired value is the electric power (W
), but in terms of device performance, it is desirable that the time required to start printing, that is, the waiting time, be short.

However, as mentioned above, it is not desirable to make the voltage applied to the discharge heater ET unnecessarily high in terms of durability of the heater.Furthermore, if bubbles are generated on the discharge heater ET during preheating, It is also difficult to increase the pulse width because it causes printing defects or non-ejection.

Therefore, in order to raise the head temperature to a desired temperature in a short period of time without affecting the durability of the heater ET and without causing foaming on the heater,
It is effective to increase the frequency of the electrical signal applied to the 8 beefs for discharging.

Figure 9 shows time (minutes) using the frequency of the preheating signal applied to 8 pieces of beef for delivery as a parameter.

An example of the relationship with the head temperature (° C.) is shown in which the applied voltage ma0 is 24v, the pulse width wt is 54g, and the frequencies are 10 KHz, 5 KHz, and 2 KHz. Note that the head temperature is detected by a temperature detection element TS.

From this point of view, the applicant conducted experiments as shown in the following two examples by changing the voltage and pulse radiation frequency.

(Example 1) 24 orifices (orifice diameter 50 x 40 IL)
Using an inkjet printer according to this example having nozzle parts NZ as shown in FIG. 3(B) in which the nozzles are arranged in a line in the vertical direction at intervals of 0.241 mm, a recording liquid having the same composition as described above was applied. The mixture was filled into an apparatus and preheated by supplying an electric signal to 8 pieces of beef for dispensing under the conditions shown in Table 2.

Then, the surface of the heater was observed using an optical microscope to confirm the presence or absence of bubble generation. The results are shown in Table 2.

Table 2 (Example 2) Using an inkjet printer similar to (Example 1), a recording liquid having the above composition was filled into the apparatus.

The durability of the heater ET was investigated by applying a signal to the discharge heater ET under the conditions shown in Table 3 and repeating the preliminary heating process. The results are shown in Table 3.

How to set these parameters and the number of pulses.

For the reasons listed above in Table 3, it can be seen that the pulse width of the electrical signal supplied to the ejection heater during the preheating process should be set to be smaller than the pulse width of the electrical signal during recording9. According to more detailed experiments by the applicant, the pulse width is preferably in the range of 1-1/20 of the pulse width during recording.

Further, it can be seen that the electric signal supplied to the ejection heater in the preheating process may be set so that the applied voltage is equal to or lower than the applied voltage applied during recording.

Furthermore, if the frequency of the electric signal during preheating is set higher than that during recording, the time required for heating can be shortened.

As described above, if the discharge time is made variable depending on the environmental conditions, this can be done very easily by setting it using the preliminary controller IO.

Next, the ejection conditions in the preliminary ejection process will be described.

If recording has been paused or stopped for a long time.

The viscosity of the ink that has remained in the orifice OR and its vicinity increases due to the evaporation of moisture, volatile quenching solvent, etc., and is in a state where it is difficult to be ejected. The viscosity of the stagnant ink can be lowered by the above-mentioned preheating treatment, but the viscosity is higher than that of ink suitable for recording, and the droplet size is high.

Since the speeds and the like are different and the noise is inappropriate for recording, in this example, preliminary heating is followed by preliminary ejection.

During the preliminary ejection process, the ejection heater ET
Since ejecting does not necessarily occur from the first pulse of the signal applied to the printer, the energy of the signal during preliminary ejection can be made greater than the energy of the signal during printing, and it is possible to shorten the time required for ejection and improve efficiency. .

The reason is to increase the energy of the signal during preliminary ejection.

Specifically, the voltage and/or pulse width may be made larger than that during recording, that is, the ejection heater ET may be used during printing.
If the voltage and pulse width of the signal applied to the Good results were obtained when the pulse width was set to 1 to 5 times, preferably 1 to 2 times, that of printing, and the pulse width was also set to 1 to 5 times, preferably 1 to 2 times.

Regarding the setting of the ejection time, the number of ejections, that is, the number of pulses, can be set according to the environmental conditions.According to the applicant's experiments, preliminary ejection after turning on the power and before starting printing (as shown in Fig. 5 (A)) In step S6 (step SJ), 1
Good print quality was obtained when 00 to 150 pulses were added to the ejection heat ET.After printing started, the viscosity of the ink was higher in a low-temperature environment, and the ejection was more stable than in a high-temperature environment. Therefore, it is preferable to set the number of times of ink ejection appropriately. In the applicant's experiments, when the low temperature side is constant (for example, 20°C) J, i (5th
In the preliminary ejection of Figure CB), when the judgment is affirmative in step Sll, the ejection becomes stable when 20 to 50 pulses are applied to the ejection heater ET, and if the temperature is below the constant temperature on the low temperature side (the negative judgment is made in step Sll). 5 for preliminary ejection (at the time of judgment)
It was confirmed that the discharge was stable when 0 to 100 pulses were applied to heater E.

Also regarding the ejection conditions for these preliminary ejections.

It is sufficient to set the controller 10 at the time of processing, and the MP
Processing can be performed quickly and appropriately without increasing the burden on U2.

Note that the area where the printer according to this example is used is limited,
If it is clear in advance, the number of ejections can be changed depending on the region.For example, in high temperature and low humidity regions, the ink is extremely dry due to constant high temperature. It is also possible to stabilize the preliminary ejection amount on the lower side than on the low temperature side, and also to change the above-mentioned value for the ejection quantity so as to obtain stable ink ejection.

In the embodiment, an inkjet printer in which a head unit is mounted on a carriage was described, but the present invention is also applicable to a so-called full multi-type inkjet printer that is equipped with a plurality of head units in the width direction of recording paper. Of course it can be done.

In addition, when setting each parameter in the preliminary heating treatment, each parameter in the preliminary discharge treatment, and the number of discharges,
In addition to being adapted to the temperature conditions as in the example, 1
For example, it can be adapted to environmental conditions such as humidity and pressure.

Furthermore, although an electrothermal energy conversion element is used in this example as the ejection energy generating means, it may also be one using, for example, a piezoelectric element.

[Effect] As explained above, according to the present invention, the head unit controller is configured to set appropriate ejection conditions and perform preliminary ejection processing before starting printing after the power source is used. This has the effect of realizing a liquid jet recording device that can quickly and easily optimize printing conditions.

Another advantage of the present invention is that the ejection conditions can be easily changed.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is a perspective view showing an example of the configuration of an inkjet printer according to the present invention. 3(A) and (1) are respectively an enlarged perspective view of the head unit and the nozzle portion of the printer shown in FIG. 1; FIG. FIG. 4 is a block diagram showing an example of the internal circuit configuration of an inkjet printer according to the present invention, a flowchart showing an example of the ffi optimization processing procedure, and FIGS. 6 and 7 are the processing steps shown in FIG. 5, respectively. 5 is a flowchart showing an example of a preliminary heating treatment procedure and an example of a preliminary ejection treatment procedure. FIG. 8 is a waveform diagram for explaining a print output signal supplied to the head unit. FIG. 9 is a characteristic curve diagram showing the relationship between supply time and temperature using the frequency of the print output signal supplied to the head unit as a parameter. MU...Liquid jet recording unit (head unit). C... Carriage, 1 R... Guide rail. TBI, TB2...supply pipe, FC...flexible cable. 5 guns...sub tank. CAP... Cap member. P...recording material. PL...Platen, S...Carriage running direction. f...recording material conveyance direction, H...home position, NZ...nozzle section, FP...front plate. IR...liquid chamber. ICH...Ink flow path. OR... Orifice. TS...Temperature detection element, )ITR...Heater for external heating. E-cho...discharge heater. N1j12. N3-...Motor. l...Program pull peripheral interface (PPI). 2...Microprocessing unit (HPυ). 3... Line buffer RAM, 4... ROM for font generation, 5... ROM for control. 6...Console, 7...Home position sensor, 8...Cap mode switch, 9...Paper sensor, 10...Head unit controller. 11.14.1B, 21, 22.24...driver,
13... Protection circuit, 15... Temperature comparison element, 16... Font selection switch. 17...Input selector. Figure 5 (Bn Figure 6 Figure 8 Figure 9 1 hour 1g! (minute)

Claims (1)

[Scope of Claims] A discharge energy generating means capable of applying energy to a liquid in response to the supply of an electric signal to form flying droplets;
a liquid jet recording unit that performs recording on a recording material by discharging the formed flying droplets; a recording unit control means for supplying the electric signal that causes the liquid droplet to be formed; What is claimed is: 1. A liquid jet recording device comprising: ejection control means for ejecting flying droplets.